On Tue, Oct 06, 2020 at 10:30:16AM +0200, Jethro Beekman wrote:
> On 2020-10-06 04:57, Sean Christopherson wrote:
> > On Sat, Oct 03, 2020 at 07:50:56AM +0300, Jarkko Sakkinen wrote:
> >> From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> >> + /* Validate that the reserved area contains only zeros. */
> >> + push %rax
> >> + push %rbx
> >> + mov $SGX_ENCLAVE_RUN_RESERVED_START, %rbx
> >> +1:
> >> + mov (%rcx, %rbx), %rax
> >> + cmpq $0, %rax
> >> + jne .Linvalid_input
> >> +
> >> + add $8, %rbx
> >> + cmpq $SGX_ENCLAVE_RUN_RESERVED_END, %rbx
> >> + jne 1b
> >> + pop %rbx
> >> + pop %rax
> >
> > This can more succinctly be (untested):
> >
> > movq SGX_ENCLAVE_RUN_RESERVED_1(%rbp), %rbx
> > orq SGX_ENCLAVE_RUN_RESERVED_2(%rbp), %rbx
> > orq SGX_ENCLAVE_RUN_RESERVED_3(%rbp), %rbx
> > jnz .Linvalid_input
> >
> > Note, %rbx is getting clobbered anyways, no need to save/restore it.
> >
> >> diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
> >> index b6ba036a9b82..3dd2df44d569 100644
> >> --- a/arch/x86/include/uapi/asm/sgx.h
> >> +++ b/arch/x86/include/uapi/asm/sgx.h
> >> @@ -74,4 +74,102 @@ struct sgx_enclave_provision {
> >> __u64 attribute_fd;
> >> };
> >>
> >> +struct sgx_enclave_run;
> >> +
> >> +/**
> >> + * typedef sgx_enclave_user_handler_t - Exit handler function accepted by
> >> + * __vdso_sgx_enter_enclave()
> >> + * @run: Pointer to the caller provided struct sgx_enclave_run
> >> + *
> >> + * The register parameters contain the snapshot of their values at enclave
> >> + * exit
> >> + *
> >> + * Return:
> >> + * 0 or negative to exit vDSO
> >> + * positive to re-enter enclave (must be EENTER or ERESUME leaf)
> >> + */
> >> +typedef int (*sgx_enclave_user_handler_t)(long rdi, long rsi, long rdx,
> >> + long rsp, long r8, long r9,
> >> + struct sgx_enclave_run *run);
> >> +
> >> +/**
> >> + * struct sgx_enclave_run - the execution context of __vdso_sgx_enter_enclave()
> >> + * @tcs: TCS used to enter the enclave
> >> + * @user_handler: User provided callback run on exception
> >> + * @user_data: Data passed to the user handler
> >> + * @leaf: The ENCLU leaf we were at (EENTER/ERESUME/EEXIT)
> >> + * @exception_vector: The interrupt vector of the exception
> >> + * @exception_error_code: The exception error code pulled out of the stack
> >> + * @exception_addr: The address that triggered the exception
> >> + * @reserved Reserved for possible future use
> >> + */
> >> +struct sgx_enclave_run {
> >> + __u64 tcs;
> >> + __u64 user_handler;
> >> + __u64 user_data;
> >> + __u32 leaf;
> >
> > I am still very strongly opposed to omitting exit_reason. It is not at all
> > difficult to imagine scenarios where 'leaf' alone is insufficient for the
> > caller or its handler to deduce why the CPU exited the enclave. E.g. see
> > Jethro's request for intercepting interrupts.
>
> Not entirely sure what this has to do with my request, I just expect
> to see leaf=ERESUME in this case, I think? E.g. as you would see in
> EAX when calling ENCLU.
The documentation needs to be fixed but the answer is yes.
I.e.
- Leaf will contain ERESUME on interrupt.
- Leaf will contain EEXIT on normal exit.
Maybe I should rename it as exit_leaf and rewrite the description to
improve clarity?
/Jarkko
